This invention relates to a molding process for producing hollow articles. In the past, hollow articles have been produced by a variety of dipping, molding and extrusion apparatus and processes. However, each of these prior art processes have suffered from disadvantages that are substantially overcome by the present process.
In the dipping processes known in the prior art, a wire is dipped into a liquified material to be formed into the hollow article. With each dip of the wire more product from the bath adheres to the coated wire until eventually the desired amount of material is built up onto the wire. Then the material coated on the wire is sufficiently hardened so as to permit the hollow article surrounding the wire to be peeled or stripped therefrom. One disadvantage of the dipping process is the large number of dips and great amount of time sometimes required to build up the desired amount of material on the wire. Additionally, when the hollow article to be manufactured requires small diameter wires, many materials are too viscous in a liquified state for the wire to be dipped therein without bending of the wire.
As with the above described prior art dipping processes, other prior art processes also have disadvantages. For instance, extrusion processes are not advantageously employed to obtain products with a closed end. Further, while prior art molding processes may be employed to obtain products with closed ends, these processes are generally not advantageously employed when the article is relatively long and slender. The reason for this is that the portion of the mold defining the hollow portion of the final product is often unstable and bends at the high pressures employed in the molding process.
The process of my invention may be employed to produce hollow products from a wide variety of materials including materials which are too viscous in a liquid state to be used to produce hollow articles by prior art dipping processes. Additionally, the process of my invention may be employed to obtain hollow products with one of the ends closed by a tip. Finally, the process of my invention may be used to manufacture hollow bodies which are relatively long and slender.